Determination of antenna noise temperature for handheld wireless devices

ABSTRACT

Antenna noise temperature is determined for a handheld wireless communication device which typically includes a radio, e.g. having a wireless transceiver and associated circuitry connected thereto, and an antenna connected to the radio. The method includes measuring an antenna thermal noise component, measuring a radio noise component, measuring an environmental background noise component, and determining the antenna noise temperature based upon the measured antenna thermal noise, radio noise, and environmental background noise components. The method may include measuring antenna efficiency, and determining further includes weighting at least one of the measured antenna thermal noise, radio noise and environmental background noise components based upon the measured antenna efficiency.

RELATED APPLICATION

This application is a continuation of Ser. No. 11/173,093 filed Jul. 1,2005, now U.S. Pat. No. 7,519,329 the entire disclosure of which ishereby incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to the field of communications devices,and, more particularly, to mobile wireless communications devices andrelated methods.

BACKGROUND OF THE INVENTION

Cellular communications systems continue to grow in popularity and havebecome an integral part of both personal and business communications.Cellular phones allow users to place and receive voice calls mostanywhere they travel. Cellular phones and other handheld wirelesscommunication devices typically include a radio, e.g. having a wirelesstransceiver and associated circuitry connected thereto, and an antennaconnected to the radio.

Antenna noise temperature has been discussed in many books and papers,such as John D. Kraus and Ronald J. Marhefka, “Antennas: For allApplications”, McGraw Hill, 2002, ch. 12; Constantine A. Balanis,“Antenna Theory: Analysis and Design” John Wiley & Sons Inc. 1997, ch.2; David M. Pozar, “Microwave Engineering”, Addison-Wesley PublishingCompany, 1993, ch. 12; J. Dijk, MJeuken and E. J. Maanders, “Antennanoise temperature”, Proc. IEEE, Vol. 115, No. 10, October 1968, pp1403-1409; and Warren L. Flock and Ernest K. Smith, “Natural RadioNoise-a Mini-Review”, IEEE Trans. on AP Vol. Ap-32, No. 7, July 1984 pp762-767.

The definitions for antenna noise temperature are mainly given based onremote sensing and satellite receiving applications, where antennas aregenerally physically away or well shielded from radio receivers and highgain antennas are used to capture weak signals. In this case the totalnoise at the terminal of the receiver antenna is mainly contributed fromthermal noise and background noise. In contrast, a wireless handheldantenna is physically very close to its receiver so that the printedcircuit board and accessories operate as a part of the antenna. Thismakes the noise contributions to the handheld wireless device antennadifferent from the noise contributions to antennas for remote sensingand satellite receiving applications.

This difference makes the standard antenna temperature definitioninadequate for explaining the receiver behavior of handheld wirelessdevices in a noisy environment. A wireless handheld device generallyoperates in an ever changing noise environment, and the handheld antennaradiation pattern is generally a broad beam antenna pattern.Furthermore, human physical interface and device usage scenarios changeconstantly in the practical application. For these reasons, antennanoise temperature is constantly changing in the practical sense.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a handheld wireless communicationdevice for use with the method of the present invention.

FIG. 2 is a flowchart illustrating steps of the method in accordancewith an embodiment of the present invention.

FIG. 3 is a schematic block diagram illustrating the various workstations to implement the method of FIG. 2.

FIG. 4 is a schematic block diagram showing basic functional circuitcomponents that can be used in the mobile wireless communications deviceof FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. Likenumbers refer to like elements throughout.

In view of the foregoing background, it is therefore an object of thepresent invention to provide a method of accurately determining theantenna noise temperature for a handheld wireless communication device.

A determination or definition of antenna noise temperature is presentedherein. Radio noise temperature is introduced to explain the radioreceiver behavior under a complex noise environment for handheldwireless devices. The noise sources and their coupling mechanisms arealso discussed. A method of determining receive sensitivity includingdetermining an antenna radiation pattern and independently determining athermal noise temperature is also provided.

These and other objects, features, and advantages in accordance with thepresent invention are provided by a method of determining an antennanoise temperature for a handheld wireless communication device includinga radio, e.g. having a wireless transceiver and associated circuitryconnected thereto, and an antenna connected to the radio. The methodincludes measuring an antenna thermal noise component; measuring a radionoise component; measuring an environmental background noise component;and determining the antenna noise temperature based upon the measuredantenna thermal noise, radio noise, and environmental background noisecomponents.

The method may include measuring antenna efficiency, and determining mayfurther include weighting at least one of the measured antenna thermalnoise, radio noise and environmental background noise components basedupon the measured antenna efficiency.

The antenna noise temperature T_(t) may be defined asT _(t) =ηT _(A)+(1−2η)T _(P) +ηT _(R)where η is measured antenna efficiency, T_(A) is the environmentalbackground noise component, T_(P) is the antenna thermal noisecomponent, and T_(R) is the radio noise component.

The antenna thermal noise component may be based upon a measuredconductive sensitivity which is based upon a minimum detectablesignal-to-noise ratio and a minimum input signal level when the antennais replaced by a signal generator. The antenna thermal noise componentT_(p) may be defined as

$T_{P} = \frac{P_{{sig}.\min}}{F \cdot {SNR}_{{out}.\min} \cdot k \cdot B}$where SNR_(out.min) is the minimum detectable signal-to-noise ratio,P_(sig.min) is the minimum input signal level, k is Boltzman's constant,B is the channel bandwidth and F is a device noise figure which isdefined as a ratio of the input signal-to-noise ratio and the outputsignal-to-noise ratio (SNR_(in)/SNR_(out)).

The radio noise component may be based upon a measured radiatedsensitivity of the communication device in an anechoic chamber at roomtemperature. The radio noise component T_(R) may be defined as

$T_{R} = {\frac{P_{{sig}.\min}}{F \cdot {SNR}_{{out}.\min} \cdot k \cdot B \cdot \eta} - \frac{\left( {1 - \eta} \right)T_{P}}{\eta}}$where SNR_(out.min) is the minimum detectable signal-to-noise ratio,P_(sig.min) is the minimum input signal level, k is Boltzman's constant,B is the channel bandwidth, F is a device noise figure which is definedas a ratio of the input signal-to-noise ratio and the outputsignal-to-noise ratio (SNR_(in)/SNR_(out)), η is measured antennaefficiency, and T_(P) is the antenna thermal noise component.

The environmental background noise component may be based upon measuredradiated sensitivity of the communication device in an operatingenvironment including a plurality of noise sources. The environmentalbackground noise component T_(A) may be defined as

$T_{A} = {\frac{P_{{sig}.\min}}{F \cdot {SNR}_{{out}.\min} \cdot k \cdot B \cdot \eta} - \frac{\left( {1 - {2\eta}} \right)T_{P}}{\eta} - T_{R}}$where SNR_(out.min) is the minimum detectable signal-to-noise ratio,P_(sig.min) is the minimum input signal level, k is Boltzman's constant,B is the channel bandwidth, F is a device noise figure which is definedas a ratio of the input signal-to-noise ratio and the outputsignal-to-noise ratio (SNR_(in)/SNR_(out)), η is measured antennaefficiency, T_(P) is the antenna thermal noise component, and T_(R) isthe radio noise component.

Objects, features, and advantages in accordance with the presentinvention are also provided by a method for determining receivesensitivity for a wireless handheld device including an antenna and aradio connected thereto. Again, the radio preferably includes a wirelesstransceiver and associated circuitry connected thereto. The method mayinclude determining an antenna radiation pattern; and independentlydetermining a thermal noise temperature by measuring an antenna thermalnoise component, measuring a radio noise component, measuring anenvironmental background noise component, and determining the antennanoise temperature based upon the measured antenna thermal noise, radionoise, and environmental background noise components. The receivesensitivity may be determined based upon antenna radiation pattern andthe thermal noise temperature.

Referring now to FIG. 1, an example of a mobile wireless communicationsdevice 20, such as a handheld portable cellular radio, which can be usedwith the present invention is first described. This device 20illustratively includes a housing 21 having an upper portion 46 and alower portion 47, and a dielectric substrate (i.e., circuit board) 67,such as a conventional printed circuit board (PCB) substrate, forexample, carried by the housing. A housing cover (not shown in detail)would typically cover the front portion of the housing. The illustratedhousing 21 is a static housing, for example, as opposed to a flip orsliding housing which are used in many cellular telephones. However,these and other housing configurations may also be used.

Circuitry 48 is carried by the circuit board 67, such as amicroprocessor, memory, one or more wireless transceivers (e.g.,cellular, WLAN, etc.), which includes RF circuitry, including audio andpower circuitry, including any keyboard circuitry. It should beunderstood that keyboard circuitry could be on a separate keyboard,etc., as will be appreciated by those skilled in the art. A rechargeablebattery (not shown) is also preferably carried by the housing 21 forsupplying power to the circuitry 48. The term RF circuitry couldencompass the cooperating RF transceiver circuitry, power circuitry andaudio circuitry.

Furthermore, an audio output transducer 49 (e.g., a speaker) is carriedby an upper portion 46 of the housing 21 and connected to the circuitry48. One or more user input interface devices, such as a keypad, is alsopreferably carried by the housing 21 and connected to the circuitry 48.The term keypad as used herein also refers to the term keyboard,indicating the user input devices having lettered and/or numbered keyscommonly known and other embodiments, including multi-top or predictiveentry modes. Other examples of user input interface devices include ascroll wheel, a back button, a stylus or touch screen interface. Thedevice 20 would typically include a display (not shown), for example, aliquid crystal display (LCD) carried by the housing 21 and connected tothe circuitry 48.

An antenna 45 is illustratively positioned at the lower portion 47 inthe housing and can be formed as a pattern of conductive traces thatmake an antenna circuit, which physically forms the antenna. It isconnected to the circuitry 48 on the main circuit board 67. In onenon-limiting example, the antenna could be formed on an antenna circuitboard section that extends from the circuit board at the lower portionof the housing. By placing the antenna 45 adjacent the lower portion 47of the housing 21, the distance is advantageously increased between theantenna and the user's head when the phone is in use to aid in complyingwith applicable SAR requirements. Also, a separate keyboard circuitboard could be used.

More particularly, a user will typically hold the upper portion 46 ofthe housing 21 very close to his head so that the audio outputtransducer 49 is directly next to his ear. Yet, the lower portion 47 ofthe housing 21 where an audio input transducer (i.e., microphone) islocated need not be placed directly next to a user's mouth, and can beheld away from the user's mouth. That is, holding the audio inputtransducer close to the user's mouth may not only be uncomfortable forthe user, but it may also distort the user's voice in somecircumstances.

Another important benefit of placing the antenna 45 adjacent the lowerportion 47 of the housing 21 is that this may allow for less impact onantenna performance due to blockage by a user's hand. That is, userstypically hold cellular phones toward the middle to upper portion of thephone housing, and are therefore more likely to put their hands oversuch an antenna than they are an antenna mounted adjacent the lowerportion 47 of the housing 21. Accordingly, more reliable performance maybe achieved from placing the antenna 45 adjacent the lower portion 47 ofthe housing 21.

Still another benefit of this configuration is that it provides moreroom for one or more auxiliary input/output (I/O) devices 50 to becarried at the upper portion 46 of the housing. Furthermore, byseparating the antenna 45 from the auxiliary I/O device(s) 50, this mayallow for reduced interference therebetween.

Some examples of auxiliary I/O devices 50 include a WLAN (e.g.,Bluetooth, IEEE 802.11) antenna for providing WLAN communicationcapabilities, and/or a satellite positioning system (e.g., GPS, Galileo,etc.) antenna for providing position location capabilities, as will beappreciated by those skilled in the art. Other examples of auxiliary I/Odevices 50 include a second audio output transducer (e.g., a speaker forspeaker phone operation), and a camera lens for providing digital cameracapabilities, an electrical device connector (e.g., USB, headphone,secure digital (SD) or memory card, etc.).

It should be noted that the term “input/output” as used herein for theauxiliary I/O device(s) 50 means that such devices may have input and/oroutput capabilities, and they need not provide both in all embodiments.That is, devices such as camera lenses may only receive an opticalinput, for example, while a headphone jack may only provide an audiooutput.

Accordingly, the mobile wireless communications device 20 as describedmay advantageously be used not only as a traditional cellular phone, butit may also be conveniently used for sending and/or receiving data overa cellular or other network, such as Internet and email data, forexample. Of course, other keypad configurations may also be used inother embodiments. Multi-tap or predictive entry modes may be used fortyping e-mails, etc. as will be appreciated by those skilled in the art.

The antenna 45 may be formed as a multi-frequency band antenna, whichprovides enhanced transmission and reception characteristics overmultiple operating frequencies. More particularly, the antenna 45 mayprovide high gain, desired impedance matching, and meet applicable SARrequirements over a relatively wide bandwidth and multiple cellularfrequency bands. By way of example, the antenna 45 may operate over fivebands, namely a 850 MHz Global System for Mobile Communications (GSM)band, a 900 MHz GSM band, a DCS band, a PCS band, and a WCDMA band(i.e., up to about 2100 MHz), although it may be used for otherbands/frequencies as well. To conserve space, the antenna 45 mayadvantageously be implemented in three dimensions although it may beimplemented in two-dimensional or planar embodiments as well.

Referring now to FIGS. 2 and 3, a method and processing system fordetermining an antenna noise temperature for a handheld wirelesscommunication device 20 will be described. As discussed above, thehandheld device 20 includes a radio, e.g. having a wireless transceiverand associated circuitry 48 connected thereto, and an antenna 45connected to the radio. The method begins at block 100 (FIG. 2) andincludes measuring an antenna thermal noise component (Block 102),measuring a radio noise component (Block 104), measuring anenvironmental background noise component (Block 106), and, at Block 112,determining the antenna noise temperature based upon the measuredantenna thermal noise, radio noise, and environmental background noisecomponents. Preferably, the method includes measuring antenna efficiency(Block 108), and weighting at least one of the measured antenna thermalnoise, radio noise and environmental background noise components basedupon the measured antenna efficiency (Block 110).

As will be described in greater detail below, the antenna thermal noisecomponent may be based upon a measured conductive sensitivity which is aratio of the minimum detectable signal-to-noise ratio and a minimuminput signal level when the antenna is replaced by a signal generator.The radio noise component may be based upon a measured radiatedsensitivity of the communication device 20 in an anechoic chamber atroom temperature, and the environmental background noise component maybe based upon measured radiated sensitivity of the communication device20 in an operating environment including a plurality of noise sources.

More specifically, for antenna noise temperature determination, one ofthe quantities by which one can define the overall performance of aradio receiver system is the signal-to-noise ratio. For a radio receiversystem, the system noise figure F is defined as input signal-to-noiseratio over output signal-to-noise ratio. It follows that

$\begin{matrix}{{F = {{SNR}_{in}/{SNR}_{out}}}{where}} & (1) \\{{SNR}_{in} = \frac{P_{sig}}{P_{n}}} & (2)\end{matrix}$P_(sig)=the input signal power per unit bandwidth,P_(n)=the input noise power per unit bandwidth,SNR_(in)=the input signal to noise ratio, andSNR_(out)=the output signal to noise ratio.

Since the overall signal power and noise power are distributed acrossthe channel bandwidth, B, the total mean square power P_(sigt) andP_(nt) can be obtained by integrating over the bandwidth. Thus for thetotal power in a channel, we haveP _(sigt) =P _(nt) ·F·SNR _(out)  (3)This equation also predicts the radio sensitivity as output signal tonoise ratio reaches its threshold.

Noise energy as a function of frequency for an ideal black body is givenby Planck's radiation law and the Rayleigh-Jeans approximation, whichholds reasonably well at microwave frequencies. Assuming conjugate matchat the receiver input and for a noise flat channel, we haveP_(nt)=kT_(t)B  (4)where T_(t)=the total temperature in degrees Kelvin (K) andk=1.380×10⁻²³ J/° K. (Boltzman's constant).

For the handheld wireless receiver, P_(nt) is the total antenna noisepower at the antenna terminal. T_(t) is the antenna temperature. Thereare various noise sources for the handheld radio receiver, and it may bedesirable that the individual noise be separable. Due to the antennaaperture size and application requirement, the handheld antennagenerally has a broad beam radiation pattern. It is more efficient andconvenient to classify the handheld noise types based on the measurablequantities. Accordingly, the handheld antenna noise temperature isclassified into three types.

The first type of noise is the antenna thermal noise. Antenna thermalnoise is caused by the random thermally excited vibration of the chargecarriers in the antenna conductor. This carrier motion is similar to theBrownian motion of particles. In every conductor or resistor at atemperature above absolute zero, the electrons are in random motion, andits vibration is dependent on temperature. The available noise power canbe in the same equation form as (4) and it isP_(P)=kT_(P)B  (5)where T_(P)=the thermal or physical temperature.

The antenna thermal noise is practically achievable in a systemoperating at room temperature. It may not be possible to achieve anylower noise unless the temperature of the receiver antenna is lowered.So it is also referred to as the “noise floor”. The thermal noisedetermines the minimum sensitivity of a radio receiver. Thermal noise isnot antenna efficiency dependent.

The second type of the noise is man-made environmental noises andbackground noises. The man-made environment noise refers to theintentional or unintentional man-made noise other than the radio noiseof its own. The man-made environmental noises include electrical andelectronics noise, such as fluorescent lights, ignitions, radiotransmitters, computers etc. The man-made environmental noise isgenerally greater than a wavelength away from the radio receiver of thehandheld device. The background noise here refers to the natural noiseincluding natural noise at the earth's surface, atmospheric noises andextraterrestrial noises. Man-made environmental and background noisescouple to the antenna through electromagnetic radiation. Due to thebroad beam pattern of the antenna, it is difficult to separate the noisesources. This type of noise is antenna radiation pattern and antennaefficiency dependent.

The third type of noise is radio noise of its own, which includes radioprocessor noise, liquid crystal display (LCD) noise and keyboard noise,etc. A handheld wireless device antenna is generally very close to theradio (much less than a wavelength). The radio noise can couple to thereceiver antenna through near-field electrical and near-field magneticfields. A handheld device antenna may use radio PCB or accessories aspart of the antenna. Thus, noise can couple to the radio through aconducted path. The conducted path is due to the antenna having sharedimpedance with the radio receiver. The near-field electrical andnear-field magnetic coupling is due to the loop or dipole kind of noiseemission from radio getting picked up by the nearby handheld antenna.The coupling efficiency of this type of noise is also antenna efficiencyand antenna type related. The better the antenna efficiency the more ofthird type of noise gets coupled to the receiver.

Thus, from the above described noise contribution, the total equivalentantenna noise temperature is determined to be the weighted average ofthe three types of noise temperature,T _(t) =ηT _(A)+(1−2η)T _(P) +ηT _(R)  (6)where η=antenna efficiency, T_(R)=the radio noise temperature, andT_(A)=the environmental background noise temperature.

The environmental background temperature received at all angles can beexpressed as follows

$\begin{matrix}{T_{A} = \frac{\int_{0}^{2\pi}{\int_{0}^{\pi}{{T_{B}\ \left( {\theta,\phi} \right)}{G\left( {\theta,\phi} \right)}\sin\;\theta{\mathbb{d}\theta}{\mathbb{d}\phi}}}}{\int_{0}^{2\pi}{\int_{0}^{\pi}{{G\left( {\theta,\phi} \right)}\sin\;\theta{\mathbb{d}\theta}{\mathbb{d}\phi}}}}} & (7)\end{matrix}$where T_(B)(θ,φ)=the distribution of the environmental temperature overall angles about the antenna, and G(θ,φ)=the power gain pattern of theantenna.

It is desirable that the three types of temperature be measurable. Themeasurement of the temperature is not only important in understandingthe radio noise characteristics, but also a very effective tool forradio design and trouble shooting. The measurement and calculationprocedure is described below with each type of the noise temperaturebeing separately identified.

A thermal temperature measurement is measured by disconnecting theantenna, and connecting a signal generator at the antenna terminal. Tothe radio receiver it is like it has a matching resistor connectedthereto. In this case, antenna efficiency is zero, from the equation (6)it can be seen that the noise temperature that the receiver is detectingis thermal temperature T_(P). For the handheld radio this process iscalled conductive measurement and the thermal temperature is equal to

$\begin{matrix}{T_{P} = \frac{P_{{sig}.\min}}{F \cdot {SNR}_{{out}.\min} \cdot k \cdot B}} & (8)\end{matrix}$where SNR_(out.min)=the minimum detectable signal-to-noise ratio, andP_(sig.min)=the minimum input signal level, i.e. radio sensitivity.

For antenna efficiency measurement, a handheld device antenna isgenerally small in size, and in a controlled environment the receiveantenna efficiency η can be measured. The receive antenna efficiency maybe measured in any one of the known methods, as would be appreciated bythose skilled in the art.

The radio temperature measurement is performed by placing the radio inan anechoic chamber at room temperature T_(P), so from equation (7) wehaveT_(A)=T_(P)  (9)Then a radiated sensitivity for the receiver can be determined. In otherwords, the radio's sensitivity is measured with the antenna connected.Then the radio temperature can be calculated from the measured radiatedsensitivity

$\begin{matrix}{T_{R} = {\frac{P_{{sig}.\min}}{F \cdot {SNR}_{{out}.\min} \cdot k \cdot B \cdot \eta} - \frac{\left( {1 - \eta} \right)T_{P}}{\eta}}} & (10)\end{matrix}$

The environmental and background temperature measurement proceeds afterthermal and radio temperature have been measured. The man-madeenvironmental and background temperature can be measured by placing theradio in a working environment, then measuring the radio's radiatedsensitivity, such that

$\begin{matrix}{T_{A} = {\frac{P_{{sig}.\min}}{F \cdot {SNR}_{{out}.\min} \cdot k \cdot B \cdot \eta} - \frac{\left( {1 - {2\eta}} \right)T_{P}}{\eta} - T_{R}}} & (11)\end{matrix}$

In the measurement process, the order of the thermal temperaturemeasurement and antenna efficiency measurement is interchangeable, butthey both should be measured before the radio temperature measurement.

It is noted that in a handheld radio receiver system the noise from theground and the surroundings of the antenna including ignition noise,electrical and electronics noise are the dominant noise source ofenvironmental temperature. The distribution function is a function ofthe specific environment and time. Since a handheld wireless antenna mayhave a broad beam antenna and, in use, the handheld orientation is alsoconstantly changing, the power gain pattern is also changing withrespect to noise source distribution. In this condition, theenvironmental temperature is changing all the time. An average antennatemperature measurement is a more appropriate approach.

Another factor that affects the antenna temperature in a real worldapplication is that the antenna efficiency changes with human physicalinterface. For example, when the wireless handheld is in the talkingposition, it will have a few dB antenna average gain degradationcompared to the stand alone position in free space. In this case theantenna temperature is generally lower than the stand alone position infree space.

So, the definition of antenna temperature determination for handheldwireless devices is general. For the remote sensing and satelliteapplication, the radio noise temperature is negligible, then equation(6) may becomeT _(t) =ηT _(A)+(1−η)T _(P)  (12)which is the same as the equation (3).

The results of the antenna temperature determination illustrate thatdifferent radio noise sources have different coupling mechanisms. Theradio noise of its own is proportional to the antenna efficiency, buthas no direct relationship with the antenna radiation pattern.Accordingly, with the antenna temperature determination of the presentinvention, handheld sensitivity and antenna pattern can be measuredseparately. The antenna temperature measurement according to the presentinvention can be used in the design and trouble shooting of handheldradios. It can also be an important factor for other radio parametermeasurements such as total isotropic sensitivity (TIS) measurement.

Referring to FIG. 3, a system 200 for implementing the above method,will now be described. The system 200 may include an antenna thermalnoise test station 202, for example, to implement the step ofdisconnecting the antenna and connecting a signal generator at theantenna terminal, to determine the antenna thermal temperature asdescribed above. A radio noise test station 204, such as an anechoicchamber, is included to determine the radio noise component, and abackground/environmental noise test station 206, such as an operatingenvironment or simulated operating environment, is included to determinethe background/environmental noise, as described above. As illustratedin the example, a calculation station 210 may determine the antennanoise temperature based upon the measured components and in view of theantenna efficiency which may be measured at the antenna efficiency teststation 208. Furthermore, the receive sensitivity of the handheld device20 may be determined based upon independent determination of the antennaradiation pattern, e.g. at the antenna pattern test station 212, and theantenna noise temperature in accordance with the above described method.

An example of a handheld mobile wireless communications device 1000 thatmay be used in accordance the present invention is further describedwith reference to FIG. 4. The device 1000 includes a housing 1200, akeyboard 1400 and an output device 1600. The output device shown is adisplay 1600, which is preferably a full graphic LCD. Other types ofoutput devices may alternatively be utilized. A processing device 1800is contained within the housing 1200 and is coupled between the keyboard1400 and the display 1600. The processing device 1800 controls theoperation of the display 1600, as well as the overall operation of themobile device 1000, in response to actuation of keys on the keyboard1400 by the user.

The housing 1200 may be elongated vertically, or may take on other sizesand shapes (including clamshell housing structures). The keyboard mayinclude a mode selection key, or other hardware or software forswitching between text entry and telephony entry.

In addition to the processing device 1800, other parts of the mobiledevice 1000 are shown schematically in FIG. 4. These include acommunications subsystem 1001; a short-range communications subsystem1020; the keyboard 1400 and the display 1600, along with otherinput/output devices 1060, 1080, 1100 and 1120; as well as memorydevices 1160, 1180 and various other device subsystems 1201. The mobiledevice 1000 is preferably a two-way RF communications device havingvoice and data communications capabilities. In addition, the mobiledevice 1000 preferably has the capability to communicate with othercomputer systems via the Internet.

Operating system software executed by the processing device 1800 ispreferably stored in a persistent store, such as the flash memory 1160,but may be stored in other types of memory devices, such as a read onlymemory (ROM) or similar storage element. In addition, system software,specific device applications, or parts thereof, may be temporarilyloaded into a volatile store, such as the random access memory (RAM)1180. Communications signals received by the mobile device may also bestored in the RAM 1180.

The processing device 1800, in addition to its operating systemfunctions, enables execution of software applications 1300A-1300N on thedevice 1000. A predetermined set of applications that control basicdevice operations, such as data and voice communications 1300A and1300B, may be installed on the device 1000 during manufacture. Inaddition, a personal information manager (PIM) application may beinstalled during manufacture. The PIM is preferably capable oforganizing and managing data items, such as e-mail, calendar events,voice mails, appointments, and task items. The PIM application is alsopreferably capable of sending and receiving data items via a wirelessnetwork 1401. Preferably, the PIM data items are seamlessly integrated,synchronized and updated via the wireless network 1401 with the deviceuser's corresponding data items stored or associated with a hostcomputer system.

Communication functions, including data and voice communications, areperformed through the communications subsystem 1001, and possiblythrough the short-range communications subsystem. The communicationssubsystem 1001 includes a receiver 1500, a transmitter 1520, and one ormore antennas 1540 and 1560. The antenna system can be designed so thatwhen one antenna is covered by a hand, performance of one or more otherantennas, including antenna gain and match, may not be degraded. Inaddition, the communications subsystem 1001 also includes a processingmodule, such as a digital signal processor (DSP) 1580, and localoscillators (LOs) 1601. The specific design and implementation of thecommunications subsystem 1001 is dependent upon the communicationsnetwork in which the mobile device 1000 is intended to operate. Forexample, a mobile device 1000 may include a communications subsystem1001 designed to operate with the Mobitex™, Data TAC™ or General PacketRadio Service (GPRS) mobile data communications networks, and alsodesigned to operate with any of a variety of voice communicationsnetworks, such as AMPS, TDMA, CDMA, PCS, GSM, etc. Other types of dataand voice networks, both separate and integrated, may also be utilizedwith the mobile device 1000.

Network access requirements vary depending upon the type ofcommunication system. For example, in the Mobitex and DataTAC networks,mobile devices are registered on the network using a unique personalidentification number or PIN associated with each device. In GPRSnetworks, however, network access is associated with a subscriber oruser of a device. A GPRS device therefore requires a subscriber identitymodule, commonly referred to as a SIM card, in order to operate on aGPRS network.

When required network registration or activation procedures have beencompleted, the mobile device 1000 may send and receive communicationssignals over the communication network 1401. Signals received from thecommunications network 1401 by the antenna 1540 are routed to thereceiver 1500, which provides for signal amplification, frequency downconversion, filtering, channel selection, etc., and may also provideanalog to digital conversion. Analog-to-digital conversion of thereceived signal allows the DSP 1580 to perform more complexcommunications functions, such as demodulation and decoding. In asimilar manner, signals to be transmitted to the network 1401 areprocessed (e.g. modulated and encoded) by the DSP 1580 and are thenprovided to the transmitter 1520 for digital to analog conversion,frequency up conversion, filtering, amplification and transmission tothe communication network 1401 (or networks) via the antenna 1560.

In addition to processing communications signals, the DSP 1580 providesfor control of the receiver 1500 and the transmitter 1520. For example,gains applied to communications signals in the receiver 1500 andtransmitter 1520 may be adaptively controlled through automatic gaincontrol algorithms implemented in the DSP 1580.

In a data communications mode, a received signal, such as a text messageor web page download, is processed by the communications subsystem 1001and is input to the processing device 1800. The received signal is thenfurther processed by the processing device 1800 for an output to thedisplay 1600, or alternatively to some other auxiliary I/O device 1060.A device user may also compose data items, such as e-mail messages,using the keyboard 1400 and/or some other auxiliary I/O device 1060,such as a touchpad, a rocker switch, a thumb-wheel, or some other typeof input device. The composed data items may then be transmitted overthe communications network 1401 via the communications subsystem 1001.

In a voice communications mode, overall operation of the device issubstantially similar to the data communications mode, except thatreceived signals are output to a speaker 1100, and signals fortransmission are generated by a microphone 1120. Alternative voice oraudio I/O subsystems, such as a voice message recording subsystem, mayalso be implemented on the device 1000. In addition, the display 1600may also be utilized in voice communications mode, for example todisplay the identity of a calling party, the duration of a voice call,or other voice call related information.

The short-range communications subsystem enables communication betweenthe mobile device 1000 and other proximate systems or devices, whichneed not necessarily be similar devices. For example, the short-rangecommunications subsystem may include an infrared device and associatedcircuits and components, or a Bluetooth communications module to providefor communication with similarly-enabled systems and devices.

Many modifications and other embodiments of the invention will come tothe mind of one skilled in the art having the benefit of the teachingspresented in the foregoing descriptions and the associated drawings.Therefore, it is understood that the invention is not to be limited tothe specific embodiments disclosed, and that modifications andembodiments are intended to be included within the scope of the appendedclaims.

1. A method of determining a receive sensitivity for a handheld wirelesscommunication device comprising a radio and an antenna connectedthereto, the method comprising: determining an antenna noise temperaturebased upon an antenna thermal noise component, a radio noise component,an environmental background noise component, and an antenna efficiency;determining an antenna gain pattern; and determining the receivesensitivity for the handheld wireless communication device based uponthe antenna noise temperature and the antenna gain pattern.
 2. Themethod according to claim 1 wherein determining the antenna noisetemperature is performed independently from determining the antenna gainpattern.
 3. The method according to claim 1 wherein determining theantenna noise temperature further comprises weighting at least one ofthe antenna thermal noise component, the radio noise component, and theenvironmental background noise component based upon the antennaefficiency.
 4. The method according to claim 1 wherein the antenna noisetemperature T_(t) is defined asT _(t) =ηT _(A)+(1−2η)T _(P) +ηT _(R) where η is the antenna efficiency,T_(A) is the environmental background noise component, T_(P) is theantenna thermal noise component, and T_(R) is the radio noise component.5. The method according to claim 1 wherein the antenna thermal noisecomponent is based upon a measured conductive sensitivity.
 6. The methodaccording to claim 1 wherein the antenna thermal noise component T_(p)is defined as$T_{P} = \frac{P_{{sig}.\min}}{F \cdot {SNR}_{{out}.\min} \cdot k \cdot B}$where SNR_(out.min) is the minimum detectable signal-to-noise ratio,P_(sig.min) is the minimum input signal level, k is Boltzman's constant,B is channel bandwidth and F is a device noise figure which is definedas a ratio of the input signal-to-noise ratio and the outputsignal-to-noise ratio (SNR_(in)/SNR_(out)).
 7. The method according toclaim 1 wherein the radio noise component is based upon a measuredradiated sensitivity of the handheld wireless communication device in ananechoic chamber at room temperature.
 8. The method according to claim 1wherein the radio noise component T_(R) is defined as$T_{R} = {\frac{P_{{sig}.\min}}{F \cdot {SNR}_{{out}.\min} \cdot k \cdot B \cdot \eta} - \frac{\left( {1 - \eta} \right)T_{P}}{\eta}}$where SNR_(out.min) is the minimum detectable signal-to-noise ratio,P_(sig.min) is the minimum input signal level, k is Boltzman's constant,B is channel bandwidth, F is a device noise figure which is defined as aratio of the input signal-to-noise ratio and the output signal-to-noiseratio (SNR_(in)/SNR_(out)), η is the antenna efficiency, and T_(P) isthe antenna thermal noise component.
 9. The method according to claim 1wherein the environmental background noise component is based uponmeasured radiated sensitivity of the wireless handheld communicationdevice in an operating environment including a plurality of noisesources.
 10. The method according to claim 1 wherein the environmentalbackground noise component T_(A) is defined as$T_{A} = {\frac{P_{{sig}.\min}}{F \cdot {SNR}_{{out}.\min} \cdot k \cdot B \cdot \eta} - \frac{\left( {1 - {2\eta}} \right)T_{P}}{\eta} - T_{R}}$where SNR_(out.min) is the minimum detectable signal-to-noise ratio,P_(sig.min) is the minimum input signal level, k is Boltzman's constant,B is channel bandwidth, F is a device noise figure which is defined as aratio of the input signal-to-noise ratio and the output signal-to-noiseratio (SNR_(in)/SNR_(out)), η is the antenna efficiency, T_(P) is theantenna thermal noise component, and T_(R) is the radio noise component.11. The method according to claim 1 wherein determining the antennanoise temperature comprises: measuring the antenna thermal noisecomponent; measuring the radio noise component generated by the radio ofthe wireless handheld communication device; and measuring theenvironmental background noise component.
 12. The method according toclaim 1 wherein the radio comprises a wireless transceiver andassociated circuitry connected thereto.
 13. A method of determining areceive sensitivity for a handheld wireless communication devicecomprising a radio and an antenna connected thereto, the methodcomprising: determining an antenna noise temperature; measuring anantenna gain pattern independently from determining the antenna noisetemperature; and determining the receive sensitivity for the handheldwireless communication device based upon the antenna noise temperatureand the antenna gain pattern.
 14. The method according to claim 13further comprising measuring antenna efficiency; and wherein determiningthe antenna noise temperature is based upon the measured antennaefficiency.
 15. The method according to claim 13 wherein the antennanoise temperature T_(t) is defined asT _(t) =ηT _(A)+(1−2η)T _(P) +ηT _(R) where η is measured antennaefficiency, T_(A) is a measured environmental background noisecomponent, T_(P) is a measured antenna thermal noise component, andT_(R) is a measured radio noise component.
 16. The method according toclaim 15 wherein the measured antenna thermal noise component T_(p) isdefined as$T_{P} = \frac{P_{{sig}.\min}}{F \cdot {SNR}_{{out}.\min} \cdot k \cdot B}$where SNR_(out.min) is the minimum detectable signal-to-noise ratio,P_(sig.min) is the minimum input signal level, k is Boltzman's constant,B is channel bandwidth and F is a device noise figure which is definedas a ratio of the input signal-to-noise ratio and the outputsignal-to-noise ratio (SNR_(in)/SNR_(out)).
 17. The method according toclaim 15 wherein the measured radio noise component T_(R) is defined as$T_{R} = {\frac{P_{{sig}.\min}}{F \cdot {SNR}_{{out}.\min} \cdot k \cdot B \cdot \eta} - \frac{\left( {1 - \eta} \right)T_{P}}{\eta}}$where SNR_(out.min) is the minimum detectable signal-to-noise ratio,P_(sig.min) is the minimum input signal level, k is Boltzman's constant,B is channel bandwidth, F is a device noise figure which is defined as aratio of the input signal-to-noise ratio and the output signal-to-noiseratio (SNR_(in)/SNR_(out)), η is the measured antenna efficiency, andT_(P) is the measured antenna thermal noise component.
 18. The methodaccording to claim 15 wherein the measured environmental backgroundnoise component T_(A) is defined as$T_{A} = {\frac{P_{{sig}.\min}}{F \cdot {SNR}_{{out}.\min} \cdot k \cdot B \cdot \eta} - \frac{\left( {1 - {2\eta}} \right)T_{P}}{\eta} - T_{R}}$where SNR_(out.min) is the minimum detectable signal-to-noise ratio,P_(sig.min) is the minimum input signal level, k is Boltzman's constant,B is channel bandwidth, F is a device noise figure which is defined as aratio of the input signal-to-noise ratio and the output signal-to-noiseratio (SNR_(in)/SNR_(out)), η is the measured antenna efficiency, T_(P)is the measured antenna thermal noise component, and T_(R) is themeasured radio noise component.
 19. A method of determining a receivesensitivity for a handheld wireless communication device comprising aradio and an antenna connected thereto, the method comprising:determining an antenna noise temperature based upon weighting each of anantenna thermal noise component, a radio noise component, anenvironmental background noise component with an antenna efficiency;determining an antenna gain pattern independently of determining theantenna noise temperature; and determining the receive sensitivity forthe handheld wireless communication device based upon the antenna noisetemperature and the antenna gain pattern.
 20. The method according toclaim 19 wherein the antenna thermal noise component is based upon ameasured conductive sensitivity.
 21. The method according to claim 19wherein the radio noise component is based upon a measured radiatedsensitivity of the handheld wireless communication device in an anechoicchamber at room temperature.
 22. The method according to claim 19wherein the environmental background noise component is based uponmeasured radiated sensitivity of the wireless handheld communicationdevice in an operating environment including a plurality of noisesources.